Liquid flow time delay switch



Sept. 2, 1941. J. A. REID LIQUID FLOW TIME- DELAY SWITCH Filed April 19, 1940 Patented Sept. 2, 1941 UNITED STATES PATENT OFFICE 2,254,710 LIQUID FLOW TIME DELAY SWITCH John A. Reid, Oak Park, Ill. Application April 19, 1940, Serial No. 330,481

17 Claims.

The Present invention relates to electric time delay switches of the liquid flow type.

One of the objects of the invention is th provision of such a time delay switch in which there is a quick break of the minimizing arcing and heating, which are due to the break of the circuit.

In the time delay switches of the prior art of this type, with which I am familiar, the break in the electric circuit is slow, and this causes electric arcing and heating and destructive action on the elements of the switch. The same is true in the devices of the prior art in the making 01' the circuit, as the conducting liquid in those devices usually flows slowly through a restricted orifice and slowly contacts the electrodes, causing heating and sputtering at the contacts of the switch.

Another object of the present invention is the provision of an improved liquid flow switch which is adapted to provide a last break or a fast make, or both, while maintaining all or the advantages which are common to liquid flow switches.

Another object of the invention is the provision of a liquid flow time delay switch of the class described, which is sturdy, economically manuused for a long periodfactured, and adapted to be of time without necessity for repair or replacement of any of its parts.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawing, in which similar characters or reference indicate similar parts throughout the several views.

Referring to the single sheet of drawings accompanying the specification,

Fig. 1 is an axial cross sectional view, taken through the insulating envelope or container of a liquid flow time delay switch constructed according to the invention. In Fig. 1 the switch is in such position that the circuit is broken at two contacts and made at two other contacts;

Fig. 2 is a view similar to Fig. 1, with the switch in another position, taken at the time when the liquid begins to flow gradually from one chamber to another, for the purpose of producing a time delay in the break or the two contacts at the right, and make of the two contacts at the left;

Fig. 3 is another similar view] 01 the switch envelope in the same position, with the conducting liquid in the position which it assumes when the time delay portion of the cycle has been iin ished and the switch is about to make a last break at the right-hand contacts and a quick make at the leit-hand contacts:

Fig. 4 is a similar view oi the switch envelope 55 the far or left end of circuit for the purpose of flow switch in the same position, with the conducting liquid in th position which it assumes after contact has been quickly broken at the right contacts and quickly made at the left contacts.

Referring to Figs. 1 to 4, the envelope or housing ll of the present liquid flow switch is preferably constructed of some suitable insulating material, such as glass, quartz, a molded phenolic condensation compound, or other materials.

The envelope It may be made by molding the envelope in two halves, in which the other parts are embedded, and fastening the two halves together, or by hollowing out the parts oi a solid block of insulating material, installing the parts, and thereafter plug ing up any apertures after the housing has been filled. The present liquid contemplates the use of two fluid mediums oi difl'erent characteristics, one of which may be an insulating gas, and a conducting liquid, or an insulating liquid and a conducting liquid.

The conducting liquid, which is indicated in' Fig. 1 at H, preferably consists of mercury, and the insulating fluid medium may consist of air or other suitable insulating gas, or it may consist of an insulating liquid.

The electrically insulating gas H, such as air or other gas at predetermined pressure, is preferred because of the greater difference in the ilow characteristics between mercury flowing through a small aperture and air flowing through a small aperture.

The general exterior shape oi the envelope or container It may be that or a tubular member with rounded ends, one end being slightly bent upward, as shown in Fig. l, to locate a chamber it above the rest of th chambers and conduits.

The insulating envelope It is preferably formed with an enlarged chamber it at one end, the left end, for example, in Fig. 1, which is adapted to receive substantially all or the conducting fluid I I.

This chamber is preferably provided with a pair of contacts l4 and i I of electrically conducting material exposed inside the chamber l3 and connected by leads it and II which pass through the wall of the envelope, and which are preferably of material or the same thermal coefficient of pansion as the material of which the envelope is made.

Thecontacts used in this switch may be of metal, such as iron or platinum which do not amalgamate, suitable for withstanding a quick break of the circuit between the metallic contact and the mercury.

The contact ll may be disposed well toward the chamber it, but is prefably provided with a pair erably toward the same side as the'contact l5, so that both leads may come of! in the same direction. Both the contacts l4 and are preferably disposed on the upper side of the chamber 13, in Fig. 1, so that there will be no failure to break the circuit by any possibility of a slight amount of mercury remaining in the chamber. Contact 15 is suitably located so that when the envelope is in the position of Fig. 3 and the mercury is in the position of Fig. 3, this contact will be uncovered, but will 'be completely and quickly covered when the mercury moves from the position of Fig. 3 to Fig. 4.

Thus there is a direct relation between the location of the contacts and the size of the chamber and the amount of mercury placed therein.

The envelope in is also provided with two more chambers i8 and i8, which together are adapted to receive substantially all of the mercury which is inside the envelope II), as illustrated in the position of Fig. 2. The two chambers I8 and I9, considered collectively, are separated from the chamber II by an inner wall 20, the upper edge of which, 2| in Fig. 2, is spaced from the uppermost part 22 or the wall of the envelope ID.

The inner wall is substantially triangular in shape, with a lower diagonally extending portion 23. The left side of the inner wall or partition 20, with the wall of the envelope ill, describes an enlarged conduit 24, through which as much of the mercury in the chamber l3 may flow into the chamber II as is necessary to fill the chamber [8 when the tube is tilted from the position of Fig. 4 to that of Fig. 1.

The chamber [8 preferably tapers downward toward its lower end, where it communicates with the chamber I! through a very small aperture 25 in a septum or diaphragm 26. The septum or diaphragm 28 may preferably consist of a metallic member of the same material as the leads l8, ll, having its edges embedded in the partition 20 and in another partition 21,

which extends downward between the chambers II and I9.

Although the aperture 25 permits mercury to flow through it slowly, air or other gases flow through it quite quickly. The chamber I! may be of any suitable shape, provided it extends upward from the aperture 25 when the switch is in a position of Fig. 4, and its outer wall is preter- 01 contacts 28, 22, exposed inside the. chamber I! to engage with the mercury, adapted to be connected with external conductors by a pair oi leads 30, II similar to the leads ll, l'l previously mentioned.

The contact 29 may be disposed near the lower end of chamber 19 when the envelope is in the position of Fig. 4, but above the residue 32 of mercury inthe trough-like portion ll of a conduit 34, between the chambers II and IS. The trough-like portion 22 of the conduit 34 is actually a liquid trap which acts as a seal for the lower part of the chamber l9 and tends to maintain the liquid in the chamber l9, due to the vacuum at the upper end of the chamber, as long as the aperture 25 is covered.

Contact 28, however, is preferably disposed near the upper end of the chamber I! in position to have its mercury in the chamber I! broken quickly when the mercury begins to evacuate the chamber i9 from the position of Fig. 3 to Fla. 4.

The conduit 34, like the conduit 24, is a relatively large one, through which mercury. will flow quite quickly. It extends from the edge 35 of an upwardly extending partition 36 downward to the lowermost portion 33 and upward again into the chamber Hi. It is important that the edge 35 shall extend above the lowermost part of the partition portion 23, when the parts are in the position of Figs. 2, 3, or 4 so that the conduit 34 may act as a trap and keep enough liquid 32 in the trap to maintain a seal while mercury is in the position of Fig. 2.

It should also be noted that the chamber I3 is substantially streamlined and provided with rounded ends for the purpose of dissipating the fence of impact of the mercury when mercury is forcibly thrown from one end of the tube to the other. The same is true of the inner wall 22 at the upper end of the tube in Fig. 2.

The inside of these chambers and conduits i3, 24, l8, l9, and 34 is preferably smooth and unbroken so that mercury will fiow quickly over the surfaces and there will be no tendency toward retention of any mercury in any crevices or pockets.

It should also be understood that the present switch may be used with any or all of the contacts I4, i5, 28, 29, or with any combinations or permutations of these four or more contacts.

For example, the contacts 14 and 15 may be omitted when it is not desired to have a time delay, after turning the switch, Iollowed by a quick make.

Furthermore, the contacts 28 and 29 may be omitted and the contacts l4, l5 use, when it is desired to have the action just mentioned; but it is not desired to have a time delay after actuating the switch, followed by a quick break.

When both sets of contacts are used, there will be a quick break at the contacts 28 and 29 and a quick make at the contacts i4 and IS.

The operation of the present time delay switch is as follows: Assuming the switch envelope ill and its mercury l i to be in the position of Fig. 1,

this envelope may be suitably turned by hand or pivotally supported so that it can be rotated through substantially ninety degrees to the position of Fig. 2.

Due to the fact that the gaseous medium I2 or air in the chamber II in conduit 24 is under suitable pressure, and due to the presence of the liquid trap 34, and the fact that it would induce a vacuum in the upper end of the chamber 1!, were the liquid to flow out of chamber l9 through trap 24, the mercury stays in the chamber l9, but begins to be slowly emptied from the chamher I! through the aperture 25 in the septum 28, through the trap 34, over the edge of partition 35.

The flow of mercury from the chamber i8 is very slow, depending on the size of the aperture and the metal or other material of which the septum is made, and the time delay may be made at any predetermined desired period within certain limits.

The mercury then continues to flow out oi the chamber is until the mercury reaches the position of Fig. 3, this lapse of time being a substantial time delay period. Thereafter the aperture 25 in the septum 22 becomes exposed to the air or other gaseous medium l2 in the chamber l8, and the air bubbles pass through the aperture 25, and bubble up into the chamber l9 to break the vacuum at the upper end of the chamber I! and permit the mercury in chamber l9 to flow down quickly through the trap 34 over the edge 35 of the partition 36 into the chamber Hi.

This latter flow of the mercury is represented by the change in position of the mercury from Fig. 3 to Fig. 4, and it takes place very quickly, producing a quick break at the contact 28 between the mercury and the contact, and eventually uncovering the. contact 29.

Thus there will be a time delay between the time when the switch is turned, which may be done manually or by any suitable actuating device, such as electromagnets, thermostats, pressure devices, or the like, and the time when the circuit is actually broken; but when the circuit is broken, it is done very quickly, thus preventing arcing, heating, and damaging of the contacts.

In regard to the quick make at the contacts I and I5, it will be noted that until the aperture 25 in the septum 26 is uncovered, only the contact I has been covered with mercury, but the contact I is still-out of contact with the mercury, as shown in Fig.3. As soon as the aperture 25 in the septum is uncovered and the mercury flows quickly out of the chamber l9, it flows as quickly into the chamber l3, to engage the contact l5, as shown in Fig. 4.

This results in a quick make of a circuit connected to the contacts l4 and I5, after'a considerably long time delay subsequent to the actuation of the switch.

When the switch is again turned back from the position of Fig. 4 to Fig. I, the mercury flows quickly away from the contacts [4 and I5, filling the chamber I8 through the conduit 24, and filling the chamber [9 through the trap 34. Any air which'may be in the conduit l8 may quickly pass upward through the conduit 24, since it will be observed that thewall 31 of the partition 20 may still slope upward towardits right end 2!, while the wall 38 of partition 21 may still slope upward toward the left, towardtrap 3|.

In other words, both of the chambers l8 and I9 are so formed as to prevent entrapment of air in them when mercury flows from the position of Fig. 4 to the position of Fig. 1. In order to assure this action, the horizontal axis of the switch may be indicated by the line A, and it will be noted that both the walls 31 and 38 slope upward toward their respective conduits, with respect to this horizontal axis. q In some embodiments of the invention, however, it may not be necessary to hold the switch to this horizontal axis, as the conduits are large enough to prevent any air entrapment and to effect quickv filling of the chambers l8 and I9. By means ofthe thin septum 26, the surface tensions of the mercury in the chambers I8 and l9 are more readily broken than they would be if there were a tubular orifice connecting the chambers.

Thus the orifice in such a septum may be made much smaller, resulting in the same positive action and quick make or break, and a longer delay action with the same quantity of mercury.

The present invention is economical in the use of mercury because the present switch does not require any more mercury to effect the time delay action. As previously stated, the invention may be embodied in switches having a make only or a quick break only, or both a quick make and break in one turn of the switch.

A switch having only the contacts 28, 29 is thus adapted to provide a time delay before the quick break at the contacts 28 and 29, and upon the return motion of the switch a quick make of the contacts 28, 29 without any delay.

Such a switch might be used, for example, for

- control of the light in the room of a residence or a. garage or on a porch, where it is desired to turn of! the light, but to have illumination for a predetermined period thereafter. For example, in a bedroom the occupant might actuate the switch,

then get in bed, and after a predetermined time delay the light would be automatically extinguished. v

As another example, the owner-cf the house might have such a switch controlling his porch light, and upon leaving the house, theporch light being on, he might actuate such a switch controlling the porch light, to turn it off, and have illumination while he walked from the porch to his car, and thereafter the time delay feature of the switch would result in extinguishment of the light, after a predetermined period oi time.

It should be understood that the present switch may be used with suitable pivotal supports, detents, etc., of a spring or other nature, for holding it in its predetermined positions and giving positive action to the knob to actuate the switch.

While I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States, is:

1. A time delay mercury switch comprising an envelope having a pair of electrical contacts exposed therein for engagement with a predetermined body of mercury, said envelope having a partition therein providing on one side of saidpartition a relatively large conduit for free fiow of the mercury backward to engage said contacts, and having on the other side of said partition a restricted orifice for delaying ilowof mercury and a reservoir formed above said restricted orifice whereby the mercury in said reservoir must first be discharged through said orifice before the orifice is exposed to permit ingress 01' gas to a part 01' the container infwhich said contacts are located, thus efiectin'g a time delay and quick break of engagement or the mercury with one of said contacts.

2. A time delay mercury switch comprising an envelope having a pair of electrical contacts exposed therein for engagement with a predetermined body of mercury, said envelope having a I partition therein providing on one side oi said partition a relatively large conduit for free flow of the mercury backward to engage said contacts, and having on the other side of said partition a restricted orifice adapted toeflect a slow fiow of mercury and a reservoir formed above said oriflce whereby the mercury in said reservoir must rst be discharged through said orifice before the orifice is exposed to permit ingress of gas to. a part of the container in which said contacts are located, thus eflecting a time delay and quick break of engagement of the mercury with one of said contacts, said envelope also'having a second chamber provided with a pair of exposed contacts for engagement with the mercury.

nd one of said contacts'being located so that it will not be engaged with mercury until the pepassed and the period of 3. A mercury switch comprising an insulating envelope and a chamber having a pair of electrical contacts exposed therein for engagement with a quantity of mercury in said envelope, and a pair of superior chambers located in said envelope, said superior chambers being adapted to be filled with the mercury, and said superior lower of said superior chambers until the aperture is exposed to gas, and thereafter the mercury flows quickly out oi the lower of said superior chambers to eifect a quick make with one of said contacts alter a time delay.

4. A mercury switch comprising an insulating envelope and a chamber having a pair of electrical contacts exposed therein for engagement with a quantity of mercury in said envelope, and a pair of superior chambers located in said envelope, said superior chambers being adapted to be filled with the mercury, and said superior chambers communicating, one with the other through a small aperture, one of said chambers being above said aperture, whereby the mercury flows slowly through said aperture and to the lower of said superior chambers until the aperture is exposed to gas, and thereafter the mercury flows quickly out of the lower of said superior chambers to effect a quick make with one of said contacts after a time delay, the lower of said superior chambers also having a pair of contacts exposed therein for a quick break after said mercury has run out 01 said superior chambers.

5. In a mercury switch a closed container formed with three chambers arranged in a series, the first communicating with the second, the second with the third, and the third with the first through relatively large conduits, and a septum interposed in one of said conduits, said septum having a relatively small aperture for slow passage of mercury and relatively fast passage of gas, said container having a predetermined quantity of mercury, and a predetermined quantity of gas therein, and electrical contact means in one of said chambers whereby mercury may flow quickly in one direction from the first of said chambers to the second and third of said chambers, but upon return fiow from the second and third of said chambers the mercury flows slowly until the orifice in said septum is exposed to gas, and thereafter quickly from the second and third of said chambers to effect a quick switch action after time delay;

6. In a mercury switch, a closed container formed with three chambers arranged ina series,

the first communicating with the second, the second with the third, and the third with the first through relatively large conduits, and a septum interposed in one of said conduits, said septum having a relatively small aperture for slow passage of mercury and relatively fast passage of gas, said container having a predetermined quantity of mercury, and a predetermined quantity of gas therein, and electrical contact means in one of said chambers whereby mercury may flow quickly in one direction from the first oi. said chambers to the second and third of said chambers, but upon return fiow from the second and third of said chambers the mercury flows slowly until the orifice in said septum is exposed to gas, and thereafter quickly from the second and third said chambers to effect a quick switch action after time delay, said container also having contacts arranged in its third chamber, and one of said contacts being located to be encased by conducting fluids only after a predetermined time delay.

7. In a liquidflow time delay switch, comprising an insulating container, said container being formed with a chamber, having a pair of electrical contacts exposed therein for engagement with a conducting fluid, a second chamber communicating with the first chamber, and having a restricted orifice for gradual flow of the conducting fluid, and quick flow of a gaseous medium, said second chamber being arranged whereby it must first be emptied of conducting fluid before the first-mentioned chamber is emptied, both said chambers communicating through the first-mentioned chamber with a third chamber in said container, and a predetermined amount or conducting fluid and gas in said container, whereby upon tilting of said container there is a time delay for a predetermined period of time, and thereafter contact between the conducting fluid and one of said contacts is quickly broken.

8. In a liquid flow time delay switch, comprising an insulating container, said container being formed with a chamber, having a pair of electrical' contacts exposed therein for engagement with a conducting fluid, a second chamber communicating with the first chamber, and having a restricted oriflce for gradual fiow of the conducting fluid, and quick ilow of a gaseous medium, said second chamber being arranged whereby it must first be emptied of conducting fluid before the first-mentioned chamber is emptied, both said chambers communicating through the firstmentioned chamber with a third chamber in said container, and a predetermined amount of conducting fluid and gas in said container, whereby -upon tilting of said container there is a time delay for a predetermined period of time, and thereafter contact between the conducting fluid and one of said contacts is quickly broken, said second and third chambers being located at substantially the same level when the tube is tilted until they are elevated, and an apertured septum located low with respect to said second and third chambers to provide said restricted orifice.

9. In a liquid flow time delay switch, comprising an insulating container, said container being formed with a chamber, having a pair of electrical contacts exposed therein for engagement with a conductingfluid, a second chamber communicating with the first chamber, and having a restricted orifice for gradual flow of the conducting fiuid, and quick flow of a gaseous medium, said second chamber being arranged whereby it must first be emptied of conducting fluid before the first-mentioned chamber is emptied, both said chambers communicating through the first-mentioned chamber with a third chamber in said container, and a predetermined amount of conducting fluid and gas in said container, whereby upon tilting of said container there is a time delay for a predetermined period of time, and thereafter contact between the conducting fluid and one of said contacts is quickly broken, said second and third chambers being located at substantially the same level when the tub is tilted until they are elevated, and an apertured septum located low with respect to said second and third chambers, the upper walls of said sec-- 0nd and third chambers sloping upward with respect to a horizontal axis when said second and third chambers are in the depressed position, to prevent entrapment of air.

10. In a liquid flow switch, the combination of tainer,

an insulating container, said container having a pair of chambers, said chambers communicating with each other through a relatively large conduit, electric contact means in one of said chambars, a supply of conducting liquid in said container, and a supply of insulating gas under predetermined pressure filling the rest of said conadapted to flow from one chamber to the other, said conduit being in the, form of a liquid trap, whereby the liquid may be retained'in one of said chambers due to the pressureof said gas, and means for breaking the vacuum in said latter chamber tocausethe liquid to run quickly from one chamber to the other, said means comprising a restricted orifice communicating with said liquid trap and adapted to delay the flow of conducting liquid, and an auxiliary chamber having a supply of liquid adapted to cover said oriflce for a predetermined period or time.

11. In a liquid fiow switch, the combination of an insulating container, said container having a pair of chambers, said chambers communicating with each other through a relatively large conduit, electric contact means'ln one of said cham bars, a supply of conducting liquid in said container, and a supply of insulating gas under predetermined pressure filling the rest or said container, adapted to flow from one chamber to the other, said conduit being in the form of a liquid trap, whereby the liquid may be retained in one of said chambers dueto the pressure of said gas, and time delay means for breaking the vacuum in said latter chamber to cause the liquid to run quickly from one chamber to the other, said means comprising a restricted orifice communi eating with said liquid trap and adapted to delay the flow o1 conducting liquid, and an auxiliary chamber having a supply 01 liquid adapted to cover said orifice for a predetermined period of 12. In a liquid flow switch, the combination of an insulating container, said container having a pair of chambers, said chambers communicating with each other through a relatively large conduit, a supply 01' conducting liquid in said container, and a supply of insulatingzgas under predetermined pressure filling the rest of said container, adapted to flow from one chamber to the other, said conduit being in the form of a liquid trap, whereby the to the other, prising a restricted orifice communicating with said liquid trap and adapted to delay the flow oi conducting liquid, and an auxiliary chamber havfice for apredetermined period of time and electrical contact means in the above said latter chamber whereby electrical contact between the contacts and liquid may be quickly broken.

13. In a liquid fiow switch, the combination of an insulating container, said container having a pair of chambers, said chambers communicating with, each other through a'relatively large conduit, 9. supply of conducting liquid in said container, and a supply oi. insulating gas under predetermined pressure filling the rest or said container, adapted to flow from one chamber to the other, said conduit being in the form of a liquid trap, whereby the liquid may be retained in one of said chambers due to the pressure of said gas, means for breaking the vacuum in said latter chamber to cause the liquid to run quickly 75 from one chamber to the other, and electrical contact means in the above said latter chamber whereby electrical contact between the contacts ing a supply 01 liquid adapted to cover said 011- pair of chambers, said and liquid maybe quickly broken, and electrical contact means located in the other or said chambers whereby'contact may be quickly made between said contact means and the liquid.

14. In a liquid fiow switch, the combination oi. an insulating container, said'container having a chambers communicating with each other through a relatively large conduit, a supply 01' conducting liquid in said container, and a supply 01' insulating gas under predetermined pressure filling the rest oi said container, adapted to flow from one chamber to the other, said conduit being in the form of a liquid trap, whereby the liquid may be retained in one of said chambers due to the pressure of said gas, means for breaking the vacuum in said latter chamber to cause the liquid to run quickly from one chamber to the other, and electrical contact means in the above said latter chamber whereby electrical contact between the contacts and liquid may be quickly broken, and electrical contact means in both of said chambers whereby a quick break-between the contact means and liquid may be effected in one chamber, and a quick make eifected between the contact means and liquid in the other of said chambers.

15. In a liquid flow switch, the combination of an insulating container, said container having a pair of chambers, said chambers communicating with each other through a relatively large conduit, electric contact means inone of said chambers, a supply of conducting liquid in said container, and a supply of insulating gas under predetermined pressure filling the rest 01' said container, adapted to flow from one chamber to the other, said conduit being in the form pl 9. liquid trap, whereby the liquid may be retained in one oi'said chambers due to the pressure of said chambers through an enlarged conduit.

16. In a time delay mercury switch, the combination of an insulating container having a pair otelectrical contacts exposed in said container for engagement with mercury, a body or mercury in said container, said container having an upwardly extending chamber joined to the other part or said container through a liquid trap and having another chamber for receiving the mercury which discharges slowly to efi'ect a time do lay, said other chamber communicating with the first-mentioned chamber through a restricted aperture, the mercury being retained in said upwardlyextending chamber upon tilting of said container while discharge is being efi'ected through said restricted aperture and trap until said restricted aperture is uncovered by mercury, whereupon the gas in said container passes through said aperture into said upwardly extending chamber causing the mercury to fiow quickly from said upwardly extending chamber to eiIect a quick switching action.

17. A mercuryswitch comprising an insulating envelope and a chamber adapted to receive a' quantity of mercury, and a pair of additional 6 write-i tro cury and to be moved to a superior position by rotating said envelope, said additional chambers communicating one with another "through a. restricted aperture, and one of said. chambers being located to be emptied first through said aperture, contact means located in one of said chambers for controlling an electrical connection through the engagement or disengagement or said mencury with said contacts, the said mercury flowing slowly through said aperture irom one caid additional chambers to the other oi caitl. odditionai apertures until the aperture is exposed to gas, and thereafter the mercury flowing quickly out of the other of said additional chambers, to efiect a. quick switching action with said contact means, after a time delay.

JOHN A. REID. 

